(a) Field of the Invention
The present invention relates to a turbine engine component having a fanned trailing edge teardrop array for improving aerodynamic and thermal performance.
(b) Prior Art
A large number of turbine blades have internal cooling passages. Often, fluid in the rearmost cooling passage is ejected externally of the blade. One such coolant ejection system is shown in U.S. Pat. No. 5,503,529 to Anselmi et al. Another such blade is shown in U.S. Pat. No. 6,164,913 to Reddy.
The Anselmi et al. patent shows a turbine blade having angled ejection slots. The ejection slots are formed in one of the airfoil sidewalls. Adjacent the slots are a plurality of tapering ribs for directing the fluid afterward. In order for the flow in a coolant passageway to enter one of the slots, the flow must turn more than 90 degrees. As a result, the Anselmi et al. blade has poor thermal performance.
The Reddy blade is similar in design to the Anselmi et al. blade. In Reddy, the ejection slots empty the coolant fluid being discharged into a trough arranged in a column immediately adjacent the trailing edge. The column of troughs is disposed in the pressure sidewall of the blade. Each trough has sidewalls which decrease in depth for blending the troughs downstream to the trailing edge. Further, the sidewalls of each trough diverge radially for distributing the coolant ejected from the slots. This blade is also suffers from poor thermal performance.
In turbine applications, coolant air flowing through film holes and trailing edge exits in the airfoil portion of a turbine blade contributes efficiency loss due to coolant injection mixing with the gas path and accelerating the coolant into the free stream velocity. The greater the angles between the free stream gas path and the coolant injection, the greater the loss of efficiency. While teardrop designs are known in the art, they have conventionally been designed axially regardless of the gas path streamline angles.